Field of the Invention
The present invention relates to a liquid-crystal display, and in particular to a vertical alignment liquid-crystal display.
Description of the Related Art
The working principle of a liquid-crystal display (LCD) is based on a mixing of light of three primary colors: red (R), green (G), and blue (B). Specifically, each pixel of the LCD is composed of three sub-pixels, a red, a green, and a blue one, and the three sub-pixels are performed with default gray level respectively to display requiring color. When the three sub-pixels are mixed in equal proportions, a white light can be obtained.
Color taste is a very important factor in design of LCD, and it may be quantified by using the CIE 1931 chromaticity coordinate system which defines colors in a plane space and may transfer the tristimulus values (X, Y, Z) of the three primary colors (red, green, and blue) to the chromatic coordinates via the following derived formulas:
  x  =                    X                  X          +          Y          +          Z                    ⁢                          ⁢      y        =                            Y                      X            +            Y            +            Z                          ⁢                                  ⁢        z            =                        Z                      X            +            Y            +            Z                          =                  1          -          x          -          y                    
Specifically, the red tristimulus value X is mainly contributed by the red sub-pixel, the green tristimulus value Y is mainly contributed by the green sub-pixel, and the blue tristimulus value Z is mainly contributed by the blue sub-pixel.
In general, a shade of white light usually occurs when the brightness of the LCD is increased. It is because the brightness gain (BZ) of the blue sub-pixel is much less than the brightness gain (RX) of the red sub-pixel and the brightness gain (GY) of the green sub-pixel and resulting in shift of the chromatic coordinates (Wx, Wy) of white light.
Therefore, an LCD which can adjust the shifted chromatic coordinates of white light to reduce the problem of having a shade of white light is needed.